2. Optical Channel and Visible-Light Tags
2.1 Optical Channel
In visible-light communication system, modulation / demodulation
technique is intensity modulation and direct detection
(IM/DD). The optical wireless channel model is
shown in Eq. (1) [4], [5]. The transmitted waveform X(t)
is the instantaneous optical power of the light wave emitter.
The received waveform Y (t) is the instantaneous current in
the receiving photo detector, which is proportional to the received
instantaneous power. We can assume that the noise
is additive white gaussian noise (AWGN).